Core B - David Elder The Pathology Core is responsible for the provision of expert pathological assistance in the interpretation of histological data to the Projects, for the development of immunohistochemical and in situ hybridization methods to enable the identification of antigens or mRNAs in archival and freshly-isolated tissues, and for accrual of residual material not required for diagnosis from human melanomas and nevi for use in the Projects. Expertise in all aspects of the pathological diagnosis and classification of melanocytic neoplasms is provided to the projects on a continuing basis, and is useful in the characterization of experimental models, as well as in the evaluation of expression of novel and experimental markers in benign, intermediate, and malignant melanocytic tumors. The Core personnel are expert in standard immunohistochemical and in situ hybridization techniques, and are very experienced in the workup of novel antibodies and probes. Under previous funding, the Core has been continuously involved in the procurement, prioritization, and provision of tissue, blood, and other biological samples for research projects. Appropriate IRB approved informed consent protocols are used. The Core maintains a shared bank of frozen tissue, and of paraffin blocks and/or sections, from melanocytic tumors, The Core has participated in the production of two tissue microarrays with cooperative groups and has access to slides from these. In addition, the Core is involved in an ongoing basis in the continuing accrual of tissues. These functions are shared with other programs, providing efficiencies that allow this Core to provide a much wider arrange of services and procurement functions than might otherwise be feasible. Biosamples are prioritized through a Tissue Allocation Committee that includes investigators from this program project, as well as from other programs. In this manner, collection, initial processing, storage if necessary, prioritization, distribution, and usage of material in the projects can be reliably tracked and optimized to ensure the best use of scarce tissue resources.